In the prior art one method of measuring torsional angular deviation employed potentiometers with sliding pick-offs. Other methods employed inductive or capacitive measuring devices. These prior art devices all had the disadvantage that the moving parts must be rigidly supported free from lost motion since the output signal is markedly dependent on the position of the moving system. In addition, the support must be arranged to exclude all translatory movements of the measuring system, particularly at right angles to its axis of rotation. In order to avoid the disadvantages referred to, complex and expensive electronic and optical devices have been proposed. The present invention provides a non-contact measurement of torsional angular deviation of a shaft even in the presence of shaft bending.